The cat, having sat upon a hot stove lid, will not sit upon a hot stove lid again. But he won't sit upon a cold stove lid, either.
— Mark Twain

Leftovers in their less visible form are called memories. Stored in the refrigerator of the mind and the cupboard of the heart.
Robert Fulghum toves quote

If variety is the spice of life, marriage is the big can of leftover Spam.
— Johnny Carson

The most remarkable thing about my mother is that for thirty years she served the family nothing but leftovers. The original meal has never been found.
— Calvin Trillin

Twas brillig, and the slithy toves Did gyre and gimble in the wabe: All mimsy were the borogoves, And the mome raths outgrabe.
— toves quotation by Lewis Carroll